Optical efficiency

Liquid scintillation counters are highly efficient for low CL intensities and consist of two photon-counting channels provided with a variable discriminator. The sample is placed between these two detectors to ensure a high optical efficiency. The discriminator is adjusted to allow photon impacts to be transmitted and small background noise pulses to be rejected. As disadvantages they suffer from saturation errors and provide nonlinear relationships between the CL intensity and the total counts. 

The modest electrical drive requbements of these diodes, and the resulting option to power the laser with standard penlight (AA) batteries, allow these CnLiSAF lasers to boast an impressive electrical-to-optical efficiency of over 4 %, which until recently" was the highest reported overall system efficiency of any femtosecond laser source. The amplitude stability of the laser output was observed to be very stable with a measured fluctuation of less than 1% for periods in excess of 1 h. These measurements were made on a laser that was not enclosed and located in a lab that was not temperature-controlled. In a more enclosed and conbolled local envbonment we would expect the amplitude fluctuations of this laser to be extremely small. While the output powers achievable from these lasers have been limited by the available power from the AlGalnP red laser pump diodes, there are already sbong indications that commercial access to higher-power suitable diode lasers is imminent. 

The increase in optical efficiency translates into increased sensitivity for sensing of gas-phase analytes. Plots of the wavenumber (v) versus the sensitivity of the HWG and a 3-m gas cell for CO and NO are shown in Fig. 7. These plots indicate that the HWG reveals increased sensitivity compared with the... 

The applicability of HWGs in FT-IR gas-sensing systems is broad. Systems have been developed to handle gas, liquid, or solid samples. The primary utility of the waveguide is its size. Small-bore capillaries used in HWG construction contribute to compact instrument design and greater optical efficiencies. Further applications will materialize as innovative sampling systems are developed. Some, like the capillary membrane, will double as preconcentrators, thus lowering detection limits for some applications. 

A high-quality GalnN/GaN MQW heterostructure was successfully fabricated by MOVPE. The fine superlattice structure was directly detected using TEM and SIMS analysis. The MQW greatly enhanced the optical efficiency in non-doped MQWs compared with the bulk GalnN layer. Consequently, the GalnN/GaN MQW is promising for die active layers of LEDs and LDs. 

The performance of LSCs which absorb light in a large area plate, and convert it into luminescence and further concentration at the edges of the plate has been well described. The optical efficiency of an LSC is given by... 

The choice of a material for LSC depends obviously on the optical efficiency which in the case of rare earth ions may be obtained from the calculated absorption and fluorescence efficiency. An efficiency of 12% for Nd doped tellurite glass has been observed [126]. 

These early tests were not conducted with the most efficient solar cells available at that time. The record efficiency then was about 30% for a laboratory cell (see Fig. 4) and those cells were not easily obtainable. Today s record efficiency is 40.7%, and 35% efficient cells are commercially available.18 Therefore, 40% solar to hydrogen efficiency is expected in the near term assuming a heat boost of 40%, a multijunction solar cell efficiency of 35%, and an optical efficiency of 85%. A 40% multijunction solar cell would yield a solar to hydrogen conversion efficiency of almost 50%. Nevertheless, electrochemical theoretical results calculated by Licht, shown in Figure 10, are consistent with these predictions based on Solar Systems early experiments.15... 

It is important to point out that most of these advantages are also shared by other nonconcentrating tubular reactors. However, the optical efficiency of CPC is near to the theoretical maximum (Rabl, 1985), as will be discussed... 

Ihe bleaching curves of the CEL layers are shown in Fig.7. Two parameters which express the optical efficiency of the CEL layers can be derived from the bleaching curves. One is the Tco/To ratio where t represents the initial transmittace of the CEL layer and T represents the transmittance of the completely bleached CEL layer. High contrast enhancement is provided by a high Wfc ratio(l). Since the three diazoniun salts have a large T /1b ratio, a good improvement in resist contrast can be expected. 

Surface defects and ligands coordinating small particles strongly suppress the luminescence and reduce the quantum efficiency. To increase the optical efficiency, the so-called core/shell structures are proposed, in... 

On the basis of published information, a set of design criteria for dye and polymer materials can be defined for optical recording. The primary function of the dye molecule is to absorb the incident laser energy. Several groups have shown that the sensitivity of dye-polymer media is largely determined by the optical eflSciency of the thin film. Optical efficiency is a measure of the optical energy coupled into the film and is a function of the dye concentration, the dye absorption coefficient, and the layer thickness. 

The photophysical properties and photostability of oxazine dye molecules for use in luminescent solar concentrators have been reported. Tests have shown that the optical efficiencies of luminescent solar concentrators prepared using a single dye in a liquid methyl methacrylate polymer are as efficient as those fabricated using the same single dye dissolved in methyl methacrylate, and which is then thermally polymerised. ... 

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